Substance Pack is bundle of 3d software, made by Allegorithmic, designed to help you create your own materials and apply them to your models.
Pack includes:
Substance Painter - tool for texturing and rendering.
Substance Designer - tool for creating amazing materials using node system.
B2M - tool for creating all required maps(Normal, AO, roughness, etc.) from the single image.
This software is subscription-based, but buying them at Steam gives you 1 year of subscription(cheaper than on official Allegorithmic site) and perpetual license after that (it means that you'll be able to use software, but will get no updates until you'll renew your subscription).
By default, pack is 25% cheaper than summary of all products prices, but today there's extra 25% discount, so it's only 50% of product's price.
So, why I'm posting this?
This tools are really good for texturing, they have good UI and there are tons of free materials avaliable for them. In my opinion, it's perfect pack for someone, who's interested in modelling + texturing, and who had no external texturing tool outside of Maya/Max/Blender/whatever else before. On top of that, it's super cheap compared to any other options.
Remember, Steam prices depends on your country, so I can't tell what's the price is for you.